Sorting and retrieving items to fill a customer order can be a laborious and time consuming. Similarly, may large organizations have extensive storage areas in which numerous items are stored. Sorting and retrieving items from the hundreds or thousands of storage areas requires significant labor to perform manually. In many fields, automated picking has developed to reduce labor cost and improve customer service by reducing the time it takes to fill a customer order. However, the known systems of automatically handling the materials are either very expensive or have limitations that hamper their effectiveness. Accordingly, there is a need in a variety of material handling applications for automatically storing and/or retrieving items.
Additionally, in conveyor or sorter systems, objects are generally transferred to or from a conveyor and/or from one conveyor to another (e.g., from a feed conveyor to a receiving conveyor). In many automated material handling systems, such transfers take place only after the object has reached a specific location (e.g., an object storage and/or retrieval location) along the conveying path. The capacity of a material handling system is determined, among other things, by the rate at which each object is transferred to and/or from the applicable location.
In some material handling systems, a conveyor may form part of a movable vehicle used to transport objects to, or retrieve the objects from, the location where a transfer operation is performed. In material systems of this type, failure to rapidly and accurately determine that an object has been transferred from or to the conveyor may delay (or prevent) the vehicle from advancing to the next location.